Speaking at a news conference in Trump Tower in New York on Tuesday, Trump repeatedly called Kristol a "loser." He said The Weekly Standard publication was "failing" and questioned Kristol's political judgment.

"He's been wrong for two years," Trump said.

Kristol soon fired back on Twitter.

"I gather Donald Trump said I'm a loser. I've won some and I've lost some, but one thing I've always tried not to be is a roaring jackass," Kristol tweeted Tuesday afternoon.

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I gather Donald Trump said I'm a loser. I've won some and I've lost some, but one thing I've always tried not to be is a roaring jackass.

Trump criticized Kristol in a series of tweets Sunday night, calling him a "dummy" and "an embarrassed loser," suggesting the pundit reflects a lack of party unity that could affect the ideological composition of the Supreme Court.

"The Republican Party has to be smart & strong if it wants to win in November. Can't allow lightweights to set up a spoiler Indie candidate!" Trump tweeted.

Bill Kristol has been wrong for 2yrs-an embarrassed loser, but if the GOP can't control their own, then they are not a party. Be tough, R's!

Mexico – "When Mexico sends its people, they're not sending their best," Trump famously said. "They're bringing drugs. They're bringing crime. They're rapists. And some, I assume, are good people." This fiery Mexico City tribute shows how this statement went down in the country.

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Photos:The Donald Trump guide to the rest of world

Germany – Kallstadt is Trump's German ancestral home. However, when Deutsche Welle contacted Trump's distant relations they elicited little more on the record than, "Hopefully this hype will ease up soon."

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Photos:The Donald Trump guide to the rest of world

Czech Republic – Clearly not content with being known just as the birthplace of Ivana, the first Mrs. Trump, the Czech town of Zlin in 2014 staged the country's largest ever pillow fight.

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Photos:The Donald Trump guide to the rest of world

Slovenia – Melania, the third Mrs. Trump, is from Sevnica. Some locals are hopeful a Trump win might lead to publicity and additional donations from Melania. (She gave to the local health clinic after the 2006 birth of their son, Barron.)

China – Trump-branded clothes that don't read "Made in Mexico" often say "Made in China." Trump explained this in 2011 by declaring, "China so manipulates their currency it makes it almost impossible for American companies to compete."